Internal combustion engines rely on high speed rotating machinery and gears that are rotating in ambient air. Resistance and friction from air surrounding the moving components of a vehicle's propulsion system contributes to fuel efficiency losses. Aerodynamic friction of the rotating and reciprocating components in the engine crankcase is conventionally mitigated with devices such as wind age trays, in order to reduce entrainment of oil droplets from the oil pan/sump into the air surrounding the engine's moving components. Entrained oil droplets further increases the drag forces acting on the engine components, thereby increasing engine load and decreasing fuel economy. Furthermore, in the power generation industry friction from air surrounding high speed electrical machinery is reduced by flooding the machinery with hydrogen gas, which has a lower viscosity than air.
The inventors have recognized certain issues with the above approaches. Namely, although wind age trays and similar devices reduce drag on engine components due to entrained oil, the drag forces due to the air surrounding the engine components is unaffected. Furthermore, hydrogen gas forms explosive mixtures with air in internal combustion engines.
One approach that at least partially addresses the above issues and that achieves the technical result of reducing friction in an internal combustion engine is to fill or partially fill the engine crankcase with a gaseous fuel such as methane. For example, the inventors have realized that by replacing air within the engine crankcase with a lower density gas, air resistance can be decreased while still providing sufficient engine cooling. Furthermore, methane gas viscosity is substantially lower than air and the flammability limits of methane in air are limited. Thus, in one embodiment, a vehicle system comprises a gaseous fuel source and an internal combustion engine including a positive crankcase ventilation (PCV) system, wherein the gaseous fuel source is fluidly coupled to the PCV system via a flow control valve, the flow control valve configured to control the flow of gaseous fuel into the PCV system. In another embodiment, a method comprises during a first condition, delivering gaseous fuel from a gaseous fuel source to the PCV system of an internal combustion engine, wherein the first condition comprises a calculated blow-by flow rate being less than a PCV valve flow rate. In a further embodiment, a vehicle may comprise a gaseous fuel source, an internal combustion engine including a PCV system, wherein the gaseous fuel source is fluidly coupled to the PCV system via a flow control valve, the flow control valve configured to control the flow of gaseous fuel into the PCV system, and a controller having executable instructions to during a first condition, deliver gaseous fuel from a gaseous fuel source to the PCV system of an internal combustion engine, wherein the first condition comprises a calculated blow-by flow rate being less than a PCV valve flow rate and a manifold vacuum being greater than a crankcase vacuum, wherein a flow rate of the gaseous fuel is calculated from a difference between a PCV valve flow rate and a blow-by gas flow rate, wherein the blow-by gas flow rate is calculated based on engine operating conditions.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.